1. Field of the Invention
The present invention relates to a rotary filling machine with injection of inert gas for filling containers with liquids. The machine in question is intended to be used in bottling plants consisting of a rotating platform (or carousel) provided peripherally with a plurality of filling valve assemblies. More precisely, the machine in question is of the gravity or partial vacuum type and may be used optimally in the sector for the bottling of beverages such as wine, mineral water, etc.
2. Description of the Prior Art
As is known, in gravity or partial vacuum machines, a liquid (for example wine) is passed from a storage tank to a container (for example a bottle) by means of gravity or with the storage tank under a partial vacuum. According to the conventional technique, each filling valve assembly is provided with an obturator which regulates the supply of the liquid into the container arranged below the valve assembly itself.
The obturator of each valve assembly is mounted inside a tubular duct designed to connect the storage tank to the container.
The duct also has, mounted inside it, an air return pipe via which, during some steps of the machine filling cycle, gas or air is expelled from the container.
As is known, the filling machines are generally preceded, in the bottling process, by rinsing machines (with or without the insertion of inert gas) aimed at cleaning the containers and reducing as far as possible the presence of oxygen inside them.
This, because one of the main problems of the bottling process is to ensure preservation of the product, preventing in particular oxidation as far as possible. In fact, as is known, the organoleptic and qualitative characteristics of some food products (such as wine) alter significantly, even if subject to a slight degree of oxidation.
Some rinsing machines used nowadays remove the air from the bottles, replacing it with inert gas (usually nitrogen or carbon dioxide), after which the bottles continue on conveyors as far as filling machines such as those in question. During this travel movement, part of the inert gas present in the (open) bottles is dispersed and replaced with air. Moreover, once filling of the bottles has been completed, extraction of the liquid supply duct creates a slight vacuum with consequent drawing-in of outside air into the bottle.
Another type of filling machine of the known type (called isobaric) solves the problem of oxidation by removing, during a first step, of all the air from the bottle (creating a vacuum of the order of 80-90% inside it) and injecting inert gas under pressure during a next step, prior to filling. This type of machine, however, is very costly, has a low productivity and requires that the bottles be subjected to pressures which may risk breaking them.
The essential object of the present invention is therefore that of overcoming the drawbacks associated with the systems of the known type by providing a rotary filling machine which allows an inert gas to be inserted inside the containers before, during and at the end of the filling step so as to reduce significantly oxidation of the product to be inserted into the containers.
A further object of the present invention is that of providing a machine which is constructionally simple and operationally entirely reliable.